Matt and Erin recap a presentation made at ICM Conference this week. Bob Koch (University of Minnesota) talked about bifenthrin failures to soybean aphid in southern Minnesota in 2015. He performed bioassays and detected resistance. The level of resistance was low, but provides the first example of this pest overcoming a pyrethroid in the field. Bob's ICM proceedings article summarizes highlights how resistance happens and strategies for prolonging insecticide efficacy. Find the proceedings free here: https://store.extension.iastate.edu/ (search for publication AEP 0302 - 2015, pages 75-76).
[Apologies for the poor sound quality of Erin's microphone]
In this podcast episode, Matt and Erin recap a few extension activities they recently participated in this week. It started with being an "expert" at the Iowa State University display building in the 2016 Farm Progress Show near Ames, IA. Both Matt and Erin helped answer questions about entomology and agriculture, and they also learned from the other displays in the building (something about underwear?). One of the main attractions was a monarch butterfly display and also samples of a new invasive weed, palmer amaranth. Matt also saw a cool UAV display with potential use in site-specific management. Erin also was a judge for a regional crop scouting competition for high school students. It included two teams each from Iowa, Indiana and Nebraska. There are some bright, young agronomists out there. Erin switched gears to talk about pest updates in Iowa, but crops are quickly maturing and the time to make treatments is generally done for this growing season.
Due to technical difficulty, this is a second take at the podcast today. Matt and Erin start by sharing highlights from the recent International Congress of Entomology (ICE) meeting in Orlando last week. Erin talks about pest resistance issues for corn rootworm and western bean cutworm. Matt summarizes some work on rapid resistance development in agro-ecology systems. Fall nuisance invaders were also briefly discussed, including minute pirate bugs, boxelder bugs and lady beetles. Matt got excited by a recent aphid find on ISU campus this week - aphids and parasitized aphids were on collected from buckthorn. They don't understand the implications for these finds yet, but it is certainly not a common find. Lastly, Matt and Erin are speaking at the upcoming ICM Conference in Ames. Registration details will be posted soon.
Minute pirate bug adult feeding on white fly nymphs. Photo at https://en.wikipedia.org/wiki/Anthocoridae.
It's the first podcasting episode of 2017! Matt and Erin talk briefly about a few topics related to insecticides today. First, Erin recaps the findings of her insecticide resistance project from 2016. A field sprayed twice with a pyrethroid (bifenthrin) did not have efficacy against soybean aphid. She conducted an assay and discovered elevated resistance ratios for bifenthrin and lambda-cyhalothrin. Distinguishing insecticide group will become important for future growing seasons so farmers can prolong the efficacy of pyrethroids and organophosphates. Learn more about insecticide groups and resistance management at the IRAC website. Matt shared updates on pending EPA approvals of existing insecticides. Chlorpyrifos, an organophosphate, had an open comment period that closed January 17, 2017; read more about the health risk assessment for chlorpyrifos. In addition, the EPA has four public comment dockets open now regarding pollinator-only risk assessments for the neonicotinoid insecticides clothianidin, thiamethoxam, and dinotefuran.
Erin and Matt are speaking at the ISU Crop Advantage Series this month. Find locations and registration details here. Erin is also speaking on a resistance management panel at the 2017 Iowa Soybean Research Conference on February 8, 2017.
Watch an IRAC video on how insecticide resistance happens!
Soybean aphid management has relied heavily on foliar insecticides to protect yield since 2000. In 2016, performance issues have been documented in commercial fields and research plots in northern Iowa counties. With support from the Iowa Soybean Association, we are exploring insecticide resistance for soybean aphid in Iowa and describing the mechanism of resistance. Laboratory bioassays identified field-collected population’s evolved resistance to pyrethroids. Read more about Monitoring soybean aphid resistance to lambda-cyhalothrin and identification of mutation associated with insecticide resistance
Host plant resistance for soybean aphid is a management tool to protect yield. Our lab has evaluated the efficacy and of host plant resistance but generally with small plot research. Working with Iowan farmers, we evaluated the efficacy of aphid-resistant soybean on commercial farms in Iowa. With funding from the North Central Region – Sustainable Agriculture Research and Education Program, we are studying the potential for aphid-resistant soybeans on a larger scale. We provided farmers with experimental and commercially available soybean varieties containing a 2-gene pyramid (Rag1+2). Read more about On-farm evaluation of aphid-resistant soybeans
With funding from the North Central Soybean Research Program, we are determining if aphid-resistant soybeans can be use with a “refuge-in-a-bag” or RIB. Refuges of pest-susceptible varieties are often included when a pest-resistant variety of a crop is used. By including a refuge, we can produce a population of avirulent aphids so that they can inter-breed and swamp out the genes of virulent aphids that are capable of surviving on the aphid-resistant soybeans. Read more about Sustainable management of host plant resistance for soybean aphid